Restarting XWiki shouldn’t have any effect on this. You need to clear your browser cache only once. If you find that it happens again, my guess is that you have several wikis with different versions of XWiki and that’s why your browser have the wrong version in its cache from time to time. Could that be it?
By “xwiki site pages” I guess you mean xwiki.org. However we haven’t touched that on xwiki.org… 
(for ex: http://www.xwiki.org/xwiki/bin/view/Roadmaps/). Do you have a link?
So you have 2 ways (see How to Remove (view source, children) - #6 by Pbas):
- Hiding the title and menu with CSS, using a SSX
- Modify the template vm:
contentheader.vmby creating a custom skin or overriding the template vm on the filesystem
How will users be able to edit content if you hide the menu? (just curious :))